1. Field of the Invention
The present invention relates to a differential gear which allows a difference in rotation between right and left driving wheels or front and rear driving wheels of an automobile.
2. Description of the Related Art
Conventionally, an automotive differential gear is generally such that pinion gears are interposed between a pair of bevel gears connected to output shafts, and the pinion gears are rotated at the time of differential motion so as to allow a difference in rotation between the output shafts. Also, as a differential gear having a differential limiting device, there is known a differential gear in which a multiple disk clutch is disposed on the back surface side of the bevel gear, and the multiple disk clutch is pressed by a thrust force of the bevel gear to produce a frictional force, by which differential is limited.
However, a mechanism for transmitting power by utilizing sliding friction in a semi-connecting state like the aforementioned multiple disk clutch has a problem in that the clutch disks produce static friction and dynamic friction intermittently in low-speed rotation, that is, a so-called stick-slip, so that a differential limiting force becomes unstable. Also, it has a problem in that noise and vibration are generated by the stick-slip.